After searching around, this is what I decided on for a gasket sealer. Locktight also sells a similar kit with a primer ,but the primer is for larger clearances and is unnecessary for this application.
I made the decision to install the seals in the cases before hand. The depth of the rear output shaft seal is critical as their is a oil hole that could be covered if its driven in a few mm too far. Installing the seals first means that caution must be taken when heating the cases that the seal is not directly exposed to the blast of the heat gun. I used sockets as a shield. I also covered all the splines with a plastic wrap to protect the seals during assembly. I used gear oil sparingly.